Lot-sizing models are a vital part of the inventory management literature. Especially dynamic lot-sizing models are the basis of many industrial applications. Besides the basic single-item model, many extensions exist and among them, remanufacturing models are important concerning aspects of quality and sustainability. They focus on the handling of product returns from customers and thus combine the processes of manufacturing and remanufacturing into a single model. While many models are focusing on this aspect of external product returns, comparatively little attention has been paid to internal product returns. Therefore, this paper introduces a basic model that assumes an imperfect production process and rework of the resulting defective items. We compare this model to the closely related models, namely the basic single-item model with perfect production and the remanufacturing model. In addition, a numeric study will compare the computation efforts for them and will also highlight hard cases of the rework model. It will be shown, that the model formulations are very similar but the computation times differ strongly for the three models thereby showing the largest runtimes for the rework model. Also, there are specific cost parameter combinations that cause multiples of the average computation times.